The subject invention is directed to the art of the manufacture of head lamp pieces, actuating pieces, or similar device provided with function symbols adapted to be illuminated by transmitted light.
Devices and methods of manufacture of the type under consideration are commonly used, for example, in association with motor vehicles for visualization of functions of motor vehicle sub-systems such as heating, illumination, or rear window heating functions. The method of manufacture produces device that are particularly well suited for application in motor vehicles and, accordingly, the invention will be described with particular reference thereto. However, it is to be understood that the invention has broader application and can be used to manufacture other luminous-type devices such as keypad keys or the like or any devices where functional symbols are to be displayed and/or illuminated by transmitted light.
One requirement for devices manufactured according to the method under consideration is sufficient visual contrast between the functional symbols and the immediate surroundings during daylight. During night time, it is also important for the device to be capable of providing adequate transmission of transmitted light when illuminated by an associated light source from behind.
Accordingly, it has been proposed to coat a homogeneous transparent and colored insert piece with a plastic material using an extrusion process. Typically, the plastic material includes raised structures formed on its surface, the raised structures corresponding in overall shape to the intended functional symbols. Typically, the surface of the colored insert piece provided with raised structures is, in part, covered with a non-transparent material. The coating process is performed in such a manner that the surfaces of the raised structures are disposed in a flush relative relationship with the surface of the extrusion-coated non-transparent material.
One disadvantage found in the above method however, is that the uniformly colored transparent insert piece can be only slightly tinted in order to assure adequate transmission of light with trans-illumination. In this case, however, the functional symbols visually contrast only slightly in direct light, such as, for example in daylight. In addition, due to variable thickness conditions, a visual perception of irregular color may result. Still further, it is very difficult using the above method to produce different colored symbols using a single insert piece. Although it is possible to use several different color insert pieces, the result is a correspondingly higher production cost.
In another method for the production of switch lenses, the functional symbols are produced by means of a multi-layer, color-imprinted plastic foil. The foil is either colored or made light-permeable only in selected areas where the functional symbols are to be located and dyed black in the remaining areas. The foil is extruded onto one side of a transparent plastic material in the areas of the device where the functional symbols are located.
One drawback with the above method, however, is that due to the extrusion from behind of the plastic foil with plastic material, particularly in cases where the finished element does not have a level surface, the foil is oftentimes stretched thus distorting the functional symbols or producing fluctuations in the thickness of the function symbols due to extension of the foil. The fluctuations in thickness result in an irregular transparency of the foil in areas of the stretched function symbols.
Lastly, another method is known for manufacturing a device of the type under consideration. The method first coats a first element consisting of clear plastic with a light, transparent color, for example white. The color coating is further covered with another non-transparent contrasting color layer such as, for example black. The function symbols are then created by removing selected areas of the non-transparent color layer to a depth up to and/or reaching into the transparent color layer.
The above method offers the benefit that due to the low thickness of the color layer, it is possible to utilize a relatively intensive color with high dye or pigment contents. This leads to a favorable compromise between an acceptably low dimming in trans-illumination and a relatively high reflection with direct light. Thus, adequate contrast can be assured in daylight as well as with illumination by transmitted light at night time or when it is dark. However, the method is very expensive and, by virtue of the method steps for manufacturing the end product, permits only the formation of function symbols having a single uniform color.
Accordingly, there is a need in the art for a method of manufacturing headlamp pieces, actuation pieces or similar pieces with function symbols for illumination with transmitted light which enables, in a very simple and cost-effective manner, manufacture of multi-color function symbols in a single basic piece. There is further a need for devices produced using the method.
The subject invention provides a method of manufacturing an apparatus with functional symbols adapted to be illuminated by transmitted light. The method includes providing a transparent support element having a first surface and at least one first raised structure extending from the first surface in a predefined area. The at least one first raised structure is shaped to represent at least one functional symbol on the transparent support element. A first transparent color layer is applied onto the at least one first raised structure in the predefined area. The first transparent color layer defines a second surface substantially parallel with the first surface. Lastly, the first surface of the transparent support element is covered with a non-transparent material in selected areas adjacent the at least one first raised structure without covering the second surface in a manner leaving the second surface exposed between portions of the non-transparent material disposed on the support element. Preferably, the outer surface of the non-transparent material extends up to but not beyond the second surface so that the resultant apparatus produced according to the method has a substantially planar face that is easily cleaned and that discourages accumulation of dust and dirt.
In accordance with a first specific embodiment of the invention, a transparent color layer is applied onto a clear or colored transparent insert piece. The insert piece has, on its surface, raised structures formed in the shaped of function elements. The transparent color layer is applied at least in the areas of the raised structures of the function elements to be produced. Thereafter, a non-transparent contrasting color layer is applied in a known fashion onto the surface of the insert piece in such a manner that the externally oriented surfaces of the raised structures remain free from covering by the non-transparent contrasting layer.
One significant advantage of the above method of manufacturing apparatus with functional symbols of the type under consideration is that it is not necessary to apply the transparent color with great precision. Rather, the function symbols are created with appropriate accuracy by means of the overall coating process in combination with the shape of the raised structures. Thus, the application of the transparent color layer relative to the surface of the function symbols can be performed over a large area. Thus, as a result, a more uniform thickness is attained and, consequently, a more uniformly illuminated symbol as well as a more uniform visual color perception and effect is enabled.
In accordance with the invention, when the function symbols are to be produced having the same color, the entire surface of the insert piece is coated with a single color layer. By applying several colors for different raised structures, multi-color designs are produced in a simple fashion inasmuch as the color layers need not have great precision in the marginal areas and, may selectively overlap.
In accordance with another aspect of the invention, the production of function symbols using different colors on a single insert piece is enabled in a simple fashion because the function symbols of the insert piece for the areas corresponding to the structures are each respectively provided with a single color layer in the desired color. Thereby, the application of the color layers, in turn, is performed without great demands as to accuracy in precision of placement of the color layers.
In accordance with another specific embodiment of the invention, the application of the non-transparent color layer is performed by extrusion coating the support element which serves as an insert piece in a manner that the surface of the non-transparent material is formed flush with the surface of the raised structure. This results in an extremely cost-effective manufacturing process, whereby the required injection mold can also be made of a simple design.
According to the invention, the method employs a color material which is known from the laser etching process. Preferably, the color material has a specific temperature stability of greater than 80xc2x0 C.
In accordance with another aspect of the present invention, in order to produce function symbols having a first color, an appropriate transparent color layer in said first color is selectively applied onto areas of the support element. The support element is thereafter coated with a non-transparent color layer without covering the colored portions thereof. To produce function symbols in the first color, the non-transparent color layer is thereafter selectively removed down to a depth exposing the transparent color layer. To produce additional function symbols in another color, multiple colors are first laid down in a stack. Thereafter, each color layer is selectively removed to depths exposing the desired color, down to the transparent support element whereupon a functional symbol is formed having the color of the support element. In areas of the insert piece where the transparent color layer is present together with the non-transparent color layer, both color layers are removed in selected regions to obtain the appropriate desired function symbol. In areas in which only the non-transparent color layer is present, only the non-transparent color layer needs to be removed in selected areas to achieve the desired function symbols having the color of the support element.
In accordance with another aspect of the invention, the transparent support element is tinted in order to tint the function symbols. Such symbols are produced by removal of all of the color layers from above the support element in selected areas to obtain the desired function symbol shaped.
In accordance with yet a further aspect of the invention, the manufacture of different color function symbols is also performed by applying, onto the transparent support element, two or more transparent color layers of different colors essentially next to each other and/or with minor overlapping of the color layers. The multiple color layers are subsequently color covered with a non-transparent color layer. Thereafter, the differently colored function symbols are then produced by selectively removing layers by first removing the superposed non-transparent color layer and thereafter removing additional layers until the desired color layer is exposed.
In accordance with yet a still further aspect of the invention, the manufacture of different color function symbols is also performed by applying several different transparent color layers on top of each other onto the surface of the support element. The creation of different color function symbols, following coating with a non-transparent layer, is then accomplished in such a manner that in each case, all color layers are removed above the particular transparent layer of color in which the respective symbol is to be created. That is, the stacked color layers are selectively removed, one after another, until the desired color of the function symbol is exposed.
In each of the above instances, the support element is preferably transparent in color, at least in the area of one or several of the function symbols. Preferably, laser etching is employed for the removal of the one or more color layers in the areas of the function symbols.
In accordance with yet another specific embodiment of the invention, the transparent and/or non-transparent layers are formed by appropriately stained transparent foils or non-transparent foils.
As can be seen from the foregoing, a primary object of the invention is the provision of an apparatus with function symbols for illumination by transmitted light and a method of manufacturing same. The manufacturing method enables an easy and cost effective process for producing such an apparatus.
Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed description.